1. Field of the Invention
The present invention is related to a base case and particularly to a fan base case.
2. Brief Description of the Related Art
The conventional base case of a cooling fan is used for being attached with a fan wheel and the combination of the base case with the fan wheel is attached to a casing of system such as a computer, a power supplier or a server corresponding to the ventilation outlet thereof. Once the fan wheel starts to run, the ambient heat of the electronic component can be dissipated outward through the ventilation outlet. Referring to FIG. 1, Taiwanese Patent Official Gazette No. 535859, entitled FAN FRAME, primarily provides a recess part 14 at the side edge 12, which is disposed outside the opening 11 of the fan frame 10, and an auxiliary intake hole 16 is formed between the recess part 14 and the opening 11 to enhance the area available for the intake air and to increase the air flow for dissipating heat.
When the fan blades 18 of the preceding conventional cooling fan 1 starts to run, the airflow can be introduced via the opening 11 and the auxiliary intake hole 16. But, due to the auxiliary intake hole 16 being disposed at the side edge 12 of the fan frame 10 outside the opening 11, a slant stop wall 13 is provided at the fan frame 10 between the auxiliary intake hole 16 and the opening 11 and turbulent flow generates at the circumferences of the opening 11 and the auxiliary intake hole 16 respectively. The turbulent flow can hit the stop walls 13 to create noise and how to reduce the noise is a subject worth us to overcome.